The invention relates to a theft-proof (preventive) system for motor vehicles of the type having a cylinder lock for doors, hoods or the like, and including a closing cylinder.
Thefts of motor vehicles are made difficult by alarm and electromagnetic locking arrangements. If these are operated by a single key from, for example, the door lock, the danger exists that this key may be copied by an unauthorized person when the vehicle is in a repair shop, parking lot, or the like, so that the vehicle could be stolen at a later date without difficulty.
This invention has as an object the construction of a cylinder lock for a theft-proof (or theft-preventive) system for motor vehicles with respect to which the described disadvantages are avoided.
According to preferred embodiments of the invention, the above-noted problem is solved by an arrangement wherein at least one locking mechanism having a closing cylinder and a switching mechanism assembly relatively translatable with respect to the closing cylinder for activating and deactivating the locking mechanism is engageable by a first key which is able to activate and deactivate only the locking mechanism, and a second key which is able to activate and deactivate both the locking mechanism and at least one auxiliary device for deterring the theft of the vehicle.
In certain preferred embodiments the cylinder lock includes an electrical contact device for an electric alarm and/or locking or other auxiliary arrangement which is actuatable by way of a first, safety key in conjunction with the operation of the closing cylinder of the lock, while with a second, operating key, the closing cylinder only is operable. To this end, it is advantageous to have the contact device structurally combined with the lock. Both keys are preferably essentially of the same length, but with the safety key of a different cross-sectioned configuration than the operating key. In this manner, a row of tumblers, arranged in double-row, are brought in contact with a contact bridge operatively cooperating with the contact device by only one of the two keys.
According to other preferred embodiments, the safety key is longer than the operating key in which case it acts together with a cylinder section beyond the closing cylinder and separated therefrom to operate the control device. A supplemental locking mechanism for arresting the closing cylinder which can be operated only with the safety key is utilized in addition to or instead of an alarm according to other contemplated embodiments. This locking mechanism may be of either the mechanical or electromagnetic type.
The advantages obtained especially with the invention may be seen in that the possibility of the separate operation of the alarm and/or locking arrangement and closing cylinder with the safety key, on the one hand, and only the closing cylinder with the operating key on the other hand, makes it unnecessary for the vehicle owner to part with the safety key such that an unauthorized copying thereof is no longer possible because, when the vehicle is in a repair shop, parking lot, or the like, only the operating key need be left with the vehicle for its operation. Thus, since the contact arrangement can be operated only with the safety key which is constructed differently in relation to its cross-section or length, than the operating key, the locking mechanism according to the present invention assures that the lock closed with the safety key cannot be opened with the operating key. Additionally, by this means, an undesired starting of the alarm device, especially by an authorized user of the vehicle, is avoided.
These and further objects, features and advantages of the present invention will become more obvious from the following description when taken in connection with the accompanying drawings which show, for purposes of illustration only, several embodiments in accordance with the present invention.